Now, we all know that not all public schools come with attached playgrounds, tracks, and basketball courts, swimming pools, etc.; but many do. I remember playing football and basketball at the elementary school near where I lived long after I was a student there. But, it never occurred to me until reading this piece that using the school's facilities wasn't encouraged—and it's possible that my friends and I may have been trespassing.

The reason that your local school isn't telling you about all the amenities it offers when school is not in session? Liability concerns. According to the Miller-McCune article:

Most public schools provide space for people to get active, like playgrounds, athletic fields, outdoor tracks, outdoor basketball courts, swimming pools and indoor gymnasiums. Although many of these are funded primarily through tax dollars, liability concerns prevent schools from encouraging their use after school hours. The logic behind this is understandable: Schools don’t want to deal with lawsuits from disgruntled joggers who twist their ankles on the track at night. Still, as a result of this approach, other parks and facilities must be built and maintained for general use, which can ultimately waste valuable resources.